The invention relates to a device for separating and discharging trimmings on a cutting machine.
It is known practice, for example through document U.S. Pat. No. 4,842,684, to automatically deposit on a mold or depositing tool, by virtue of a robot furnished with a drape-molding head, a strip or a sheet of fibers for the manufacture of various parts such as aircraft wings, based on a composite strip consisting of bonded fiber elements (carbon, glass, Kevlar®, etc.), by impregnation of a heat-curable or thermoplastic resin, and supported on a backing tape made of paper or of plastic film. The composite tape is unwound from a reel in order to pass over the drape-molding head where the tape of prepreg fibers is separated from the backing tape, the latter being returned to a winding mandrel, while the prepreg is applied to the mold or the previous layers already deposited, via a compacting member usually consisting of a roll or an applicator shoe connected to the drape-molding head.
Because of the shapes of the parts produced, and notably because of their edges, it is necessary not only to deposit “full width” sections of tape, with four sides, but also sections of various shapes, obtained by complex cutting of the tape. The section which will be deposited is called a “panel” and the section between the cutaway panels is called the “trimming” which will be discarded.
For the simple-shaped through-cuts, a single-phase deposit process is used which comprises the cutting in situ of the strips to be deposited and their immediate depositing by the same machine. A mechanical or ultrasonic knife cuts the prepreg tape directly on its backing paper without cutting the latter which will be rerolled onto the mandrel after stripping.
For the strips to be cut in complex shapes, the Applicant has perfected a two-phase method, according to which the cutting is carried out upstream of the depositing process itself, with a first specialized machine in which the successive precut sections are deposited on a backing tape or between two protectors and wound onto a cassette installed on the drape-molding head.
This first machine therefore carries out the cutting of the panels, the stripping of the paper backing, the discharging of the trimmings and the repackaging of the panels.
The Applicant has also disclosed, in document FR 2 656 290, a device for separating and discharging trimmings cut away in a strip of material, in which the trimmings are diverted from their rectilinear path by a suction roll and they are discharged by removal rolls. FIG. 1 of the present document shows the prior art. The strip is presented upstream of the device in the form of a complex 3 linking together a thickness of backing tape 1 and a thickness of prepreg 2 which has been previously cut away on the backing tape without cutting the latter by cutting means not shown upstream of the device. The prepreg 2 usually consists of uni-directional carbon fibers immersed in a flexible matrix of bonding resin. There are therefore in the cutaway prepreg 2 useful zones 2′ called panels which must be retained and will be repackaged and trimmings zones 2″ which must be discharged by the device. The latter essentially comprises a suction roll or drum 10 comprising suction zones of adjustable extent. Just upstream of the drum 10, a stripping edge 11 makes it possible to strip the backing tape 1 so that only the prepreg 2 passes in front of the active portion of the drum 10. If there is suction, which the control program initiates as a function of the cutaway elements of the prepreg 2, the part 2″ to be discharged follows the periphery of the drum 10 and is rapidly collected by removal rolls 12 in order to be carried to a waste can. If there is no suction, the retained portion 2′ of prepreg 2 continues its rectilinear path in order to be collected in a repackaging jaw formed by two linked rolls 13 which deliver around the retained cutaway elements or panels 2′ two repackaging films 14 so as to form downstream a complex 4 of cutaway elements of repackaged prepreg which will be wound onto a cassette in order to be used in a depositing machine.
According to this known device, there is a transfer zone A, between the nose of the stripping edge 11 and the repackaging jaw 13, where the panels 2′ that are to be repackaged are not guided.
Finally, with this method, during the deposition, the side of the deposited panel is inverted relative to the strips deposited by the depositing machines in the single-phase method.
Known through document WO 01/56754 is a device which makes it possible to separate the cutaway elements produced in a sheet of metal or of cardboard by virtue of a diversion roll which directly sets aside the cutaway sheet considered to be a trimming and leaves the cutaway elements to be stacked downstream of the device. To the extent that it is not a cutting of prepregs, that is to say of bonding elements, which must be deposited on a backing strip, this document does not relate to the problem of the invention, namely the correct positioning of the prepregs after the discarding of the trimmings.